Morphologic alterations of sulcular and junctional epithelium have been associated with the transformation of chronic periodontal lesions into aggressive, destructive lesions. The factors responsible for these alterations are not completely understood. The purpose of the proposal investigation is to determine the effects of substances derived from dental plaque bacterial on human stratified squamous epithelium maintained in vitro. This model may provide information which will increase our understanding of the direct effects of plaque on oral epithlium in periodontal disease. Cell wall and cytoplasmic components of Bacteroides assacharolyticus will each be added to keratinoxyte cultures. Effects on the keratinocytes will be determined by analysis of the following: quantitation of cell growth, ultrastructural morphology, permeability, and production of keratin-like proteins. Other organisms assiciated with dental plaque will also be screened by determining their effect on growth and morphology of keratinocytes. These include the pathogens Actinobacillus actinomycetemcomitans and Capnocytophaga; and the non-pathogens Strep. mitis and oral neisseria.